This week’s topic was weeds. Starting with weed identification and methods of prevention and control. It was handy that Jo had already started pointing out common weeds during the propagation classes, otherwise I wouldn’t have been able to name many at all. There have been a few lessons now around identification and I’m slowing increasing my knowledge.
A weed is in essence just an unwanted plant, growing somewhere you don’t want it to. They are usually vigorous growers and compete for nutrients, light and space which is what makes them undesirable in gardens or crops. Some are poisonous and can host pests and diseases. In crops they can interfere with machinery and limit spray penetration.
Weeds could be considered beneficial in some instances. They increase the diversity of insects, therefore increasing the amount of predator insects, which is particularly important in organic operations where pesticide isn’t used. The larvae of one hover fly can eat 400 aphids. Since they compete for resources they can be helpful in managing a vigorous crop that needs to be held back. Weeds also help add organic material back into the soil.
Another feature is that they can germinate very quickly and produce huge amounts of seeds which can be dormant in the soil for many years until the right conditions come along.
On Wednesday we took a break from weeds to learn about soil testing. A vineyard or orchard would soil test once a year, usually after harvest in winter, to check the nutrient levels. Standard things to check are pH levels, phosphorus, potassium, calcium, magnesium, sodium, sulphur, boron and zinc. Nitrogen is not tested for since the sample would degrade before it could be analysed.
Once you have the results you can plan for the fertilisers needed to correct any imbalances. In Central Otago fertilisers start being applied in mid-October, after most of the morning frosts have stopped.
Speaking of frosts…while we were at the Bannockburn Road we checked the frost fighting equipment that protects the vines and cherry trees to make sure it was all working correctly. A few were spraying water all over the place, but we had them fixed pretty quickly.
Frost fighting will start in about two weeks time. Overhead irrigation is one of the most effective ways to fight frost. It will protect down to about -5 degrees while wind machine systems will only work down to about -2.
On Thursday we did some work in the potting shed, sowing tomato seeds, pricking out seedlings from seed trays to on into individual pots and re-potting trees that have been grown from cuttings.
I checked in on the chives from a couple of weeks ago – they are looking good!